Photoresponsive melittin having a spyropyran residue in the hydrophobic region of the sequence
Abstract
A melittin derivative carrying a spiropyran group at the third residue (MSp) was prepared by a semisynthetic method. MSp showed reversible photochromism in a phospholipid bilayer membrane. The kinetics of thermal decolouration and the maximum absorption of MSp in the merocyanine form indicated that the merocyanine moiety is located at the membrane surface. The disturbance of the membrane structure by MSp, as studied by CF leakage, was enhanced by UV-light irradiation. The kinetics of CF leakage indicate that MSp in the merocyanine form disturbs the membrane structure more significantly than that in the spiropyran form.